Direct flex

ABSTRACT

A one way action golf club flex modification system mounted within a golf club. The non-linear shape of the flex modification member engages the interior wall of the hollow shaft at two regions on opposite sides of the shaft interior and is affixed to a third point in the handle. The “free” end of the flex modification system is closest to the head and generally oriented toward the striking face of the head. The one way action reduces the flexibility of the shaft during the swing toward the golf ball but allows the shaft to flex forward with the travel of the ball. The plane described by the waive shape of the flex member may be fixedly rotated relative to the shaft to allow fine tuning to accommodate the individual swing of the golfer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to modifying the flex of a golf club shaft by introduction of a one way action flex modification assembly.

2. Description of the Related Art

Improvements to golf clubs with intent to improve distance and accuracy of golf ball travel are old in the art. These include modifications of and add-on devices to the major components of golf clubs. The golf club shaft has received much of this attention especially in conjunction with hollow shafts. Elements introduced into tubes to enhance rigidity are very old and would appear in almost any art where tubing rigidity was an issue. There are major groups of these modifications wherein the enhancement is: either inserted and removable; inserted and affixed or integral to the forming of the tube structure and either affects the flexibility in one plane or radially. Golf club and other implement shaft flex modifications have appeared in those forms with the addition of some inserts being radially index-able. Other shaft flex modifications utilize the shaft itself as part of the system to modify the overall flexibility of the club by creating tension or compression on a region of the shaft. One-way action is cited by some inventors when a close analysis reveals the modified action is actually in one plane of motion and therefore would modify the flex of the shaft as it is swung in either fore or aft in that plane.

U.S. Pat. No. 2,992,828 issued to Stewart in 1961 discloses a system to modify the flexibility of a golf club shaft which claims to limit shaft flex on the leading side of the shaft during the down stroke. 828 attempts to accomplish its utility by two main embodiments of using a tensioned wire in the leading side of the shaft or a column member with compression force exerted on the opposite side. In either embodiment 828's influence on the flex of a golf shaft is limited by its inherent tendency to bow the shaft as the shaft is preloaded. In 828 the shaft itself is a structural member of the tension style system which seeks to modify flexure of the shaft. The present invention has a true distal one sided affect on the flexibility of the shaft, is radially index able and can be produced with high rigidity and installed without bowing the shaft. The shaft of the present invention is not impeded from flexing toward the direction of swing after the initial impact with a golf ball.

U.S. Pat. No. 3,833,223 issued to Shulkin in 1974 discloses shaft inserts of various flexibility that reduce the overall flexibility of the shaft and insert combination. 233 is directed toward a test club system to assist selecting available shafts based on desired total flexibility to facilitate producing a custom club from standard parts.

U.S. Pat. No. 5,226,652 issued to Sato in 1993 discloses a neck portion added between the head and shaft of a golf club. The neck may include a core. The core may be made of various strength material and includes a rod passing through the middle which may be tensioned against end plates creating compression on the core material. The chief function of the invention is to modify the wave form flex of the shaft near the head at the moment of impact with a golf ball which is aggravated by the head being offset from the shaft. The rod passing through the neck is present to modify the action of the core filler material. Unlike the present invention 652 acts to change the flexibility in all directions around the shaft and therefore indexing has no effect and it requires a permanent physical modification of the club. The present invention would accommodate a golfer selecting different strength inserts as their swing improves and ultimately removing the inserts so that the club would conform to regulation play.

U.S. Pat. No. 6,280,347 issued to Herber in 2001 discloses annular rings that are permanently affixed to the exterior of the club shaft. Those structures affect the flexibility of the shaft region they are attached thereby directing forces that cause shaft flex into other areas of the shaft. 347 differs from the present invention in that its flex modification acts in all directions around the shaft and the structures are permanently attached to the shaft.

U.S. Pat. No. 6,113,508 issued to Locarno in 2000 discloses a shaft flex modifying insert within a hollow shaft that has different flexibility in one direction than another direction. The disclosed insert may be rotated within the hollow shaft to index the insert relative to the hollow shaft. However, even though 508 claims different flexibility in one direction than another the device actually affects flexibility in a plane as there is no claim or insinuation that the insert's chief affect would be on one side of the hollow shaft. Installed in a golf club shaft the 508 insert would affect both the front and back swing in a given plane.

U.S. Pat. No. 6,241,623 issued to Laibangyang in 2001 discloses a golf club shaft flex modifying system which basically consists of a variable tensioned centrally mounted wire with anchors at each end of the shaft. The apparent novelty of 623 is that it enables the player to readily adjust the tension while playing. Also present are a plurality of wire supports spaced in the shaft to help maintain the wire's centricity during any flexure. Increasing the tension on the central wire tends to exert a compressive force on the shaft section between the anchors thereby modifying the characteristics of the shafts reaction to force exerted by the swing and impact with the golf ball. Again, unlike the present invention 623 modifies the flex characteristics of the shaft at all radial angles and requires a distal anchor that may not be readily removable.

U.S. Pat. No. 6,394,909 also issued to Laibangyang in 2002 discloses a golf club shaft flex modifying system which is very similar to 623. 909 further discloses and claims a tensioned wire and an embodiment includes the central tensioned wire of flat cross section accommodated by the anchor ends. This embodiment further includes wire supports with a slot shaped bore. 623 and 909 both utilize the shaft itself a structural members of the flexure modifying system.

The current invention acts on the shaft without using the shaft as part of its own structure. Due to its generally three contact point shape it engages the lower end of the shaft on one side only. The distal end of the shaft would be allowed to flex away from the insert but engage the rigidity of the insert as any force attempted to flex the shaft toward the distal contact point. The forces given major consideration here are the inertia of the distal end of the shaft and head as a golfer begins a swing which tends to bend the shaft and head away from the swing and the forces at the moment of impact with the golf ball. Inserts with differing rigidity and an index able retainer allow customization of the affects of the insert. The insert may be installed in the proximal handle end of the shaft without modification of the shaft which may be returned to its prior condition. 

1. A golf club assemble with adjustable shaft flex modifier comprising: a commercially available or custom built golf club having an elongated hollow shaft; said hollow shaft has a head end a length and an opposite handle end which is open; a tension rod; said tension rod having a proximal end, length and distal end and being made from material of a predetermined modulus of elasticity over its length and bent at a predetermined angle at a predetermined distance from said distal end; a turning bar; a locking means; a turning means said turning bar having a first end, a body and a second end; said body and at least said second end and some portion of said body defining a tension rod aperture adaptive to fixedly receive said tension rod proximal end and some portion of said length and said body outer surface defining a cylinder and said second end defining a depression or protrusion adaptive to engage ably receive said turning means and said body accommodating said locking means; a stop ring; said stop ring having a first end, a body and a second end; said first end and body defining an aperture adaptive to rotatably receive said turning bar and said second end defining a stop ledge aperture which is less than the aperture of said body and said stop ring body outer surface defining a profile concomitant to the inner profile of said golf club opposite handle end; a stop ring securing means; said securing means attaches said stop ring to said golf club shaft; said locking means selectable engaging said turning bar to said stop ring; and said stop ring mounted in said golf club handle end with said stop ring second end toward golf club head, said tension rod proximal end mounted in said turning bar, said tension rod inserted in said golf club shaft distal end first until said turning bar fully engages said stop ring, said turning bar rotated until said tension rod distal end is in a predetermined position relative to said head and said locking means engaged.
 2. The assembly of claim 1 wherein said turning bar and said stop ring are unitary and said locking means engages said golf club shaft directly.
 3. The assembly of claim 1 wherein said tension rod modulus of elasticity varies by predetermined values over its length.
 4. The assembly of claim 1 wherein said tension rod has at least a partial length of non circular cross section.
 5. The assembly of claim 1 wherein said tension rod is a composite material.
 6. The assembly of claim 1 wherein said tension rod further comprises: a distal rub block and a bend rub block; both said rub blocks have a rod side, a height, a thickness and a shaft side; both said rub blocks rod sides are affixed to said tension rod at their respective positions; and both said blocks shaft side profiles approximate the inner profile of said hollow shaft at their respective installed positions. 